1. Field of the Invention
The present invention relates to the field of photography and lighting. More particularly, the present invention relates to the field of mobile device attachments for measuring light intensity.
2. Background of the Invention
To determine the appropriate exposure settings for a photograph, the lighting conditions under which the photograph is taken needs to be measured. A photographer might use one of two different types of light meters to make this measurement: a) a reflected light meter, or b) an incident light meter.
Reflected light meters are typically stand-alone handheld devices or integrated into a camera. The reflected light meters built into most modern cameras can measure the amount of light reflected off of the subject and background scene and into the camera.
Incident light meters are usually a stand-alone handheld device. The typical usage of an incident light meter is to place the meter near the subject and taking a measurement. The light projected onto the meter is the incident light.
Measurement by reflected light using a reflected light meter is far more convenient and expedient and, in most cases, adequate for determining the appropriate exposure settings. However, when a scene contains a more than or less than an average amount of light, the use of a reflected light meter can result in a photograph that is underexposed or overexposed. In such cases, an incident light meter typically provides better exposure results. A photographer can place an incident light meter on the same plane as the subject to be photographed to measure the amount of actual light incident on the subject. This light measurement would then be used to determine exposure settings that are more appropriate than those that would be obtained through the use of a reflected light meter.
It can be seen that reflected light meters and incident light meters each have advantages and disadvantages. A reflected light meter can be built in to a camera, thus freeing the photographer from the need to carry an additional piece of equipment. A camera with a built-in reflected light meter can use the light level measurements made by the reflected light meter to make an automated determination of the appropriate exposure settings. However, the light level measurements made by a reflected light meter may not provide the most appropriate exposure settings when a photographed scene contains challenging light conditions.
An incident light meter, on the other hand, can take light level measurements that result in exposure settings that are correct under a broader range of lighting conditions. However, a photographer using an incident light meter typically needs to carry an additional piece of equipment and may need to manually determine the exposure settings based on the measurements made by the incident light meter.
Digital cameras are sometimes included in multi-function or telecommunication devices such as mobile phones, smart phones, personal digital assistants, tablet devices, laptop computers, or other similar portable electronic devices. Any such device will hereinafter be referred to as a mobile telecommunications device or simply, a mobile device.
Since mobile devices are ubiquitous in today's society, a device that enables a photographer to use a mobile device camera as an incident light meter is therefore desirable. It may also be desirable for a non-photographer to use an incident light meter, for example, to measure the ambient light in an office or home environment.